This invention relates to the ball mount component of a trailer hitch having multiple hitch balls mounted on a rotating plate, and a trailer hitch incorporating such a ball mount component.
A trailer may be connected to a vehicle via a trailer hitch. The trailer hitch is attached to a vehicle and typically includes a hitch ball positioned at an appropriate height off the ground to engage the tongue of the trailer. A coupler at the end of the trailer tongue fits over the hitch ball and locks into place, allowing the vehicle and trailer to pivot in relation to each other, for example, when making turns, but prevents separation. The “ball mount” is the component of the trailer hitch that includes the hitch ball(s) and the supporting structure for the hitch ball(s).
In the United States, trailer hitches are rated according to weight capacity, in particular gross towing weight (the gross weight of the trailer and its load) and tongue weight (the downward force of the trailer tongue on the hitch ball). Class I hitches are for towing up to 2,000 lbs. gross trailer weight and up to 200 lbs. tongue weight. Class II hitches are for towing up to 3,500 lbs. gross trailer weight and up to 350 lbs. tongue weight. Class III hitches are for towing up to 6,000 lbs. gross trailer weight and up to 600 lbs. tongue weight. Class IV hitches are for towing up to 12,000 lbs. gross trailer weight and up to 1,200 lbs. tongue weight. Class V hitches are for towing gross trailer weights greater than 12,000 lbs. and tongue weights greater than 1,200 lbs.
The coupler on the trailer tongue and the hitch ball are available in different sizes, and it is necessary to match the size of the coupler and the hitch ball, to ensure proper operation during towing. For example, in the United States, common hitch ball sizes range from 1⅞″ to 3″, measured as the diameter of the hitch ball. Accordingly, when switching from one trailer to the next, it is often necessary for the driver of the vehicle to switch the hitch ball, to accommodate the size of the trailer's coupler.
One method of facilitating the switch from one size hitch ball to another has been to provide a ball hitch assembly having multiple hitch balls. In U.S. Pat. No. 6,315,316 B1, Wyant discloses a turntable having multiple hitch balls bolted to it. In particular, the hitch balls are mounted on the turntable by a threaded stud, extending downward from the hitch ball and through the turntable, and held in place with a nut. A spacing member is interposed between the turntable and the supporting shaft of the ball mount, to provide sufficient clearance to allow the turntable to rotate. The spacing member creates a “moment arm” between the turntable and the supporting shaft, however, which is undesirable and can limit the weight that can be towed by the trailer hitch.
A trailer hitch having selectable, multiple hitch balls is disclosed in Ross, U.S. Pat. No. 6,497,428 B2. The multiple hitch balls are mounted on a revolving plate, which is supported by a “base plate” welded to the support shaft. A locking pin may be inserted through holes in the revolving plate and base plate, to hold a hitch ball in a desired position. The use of a base plate in the ball mount mechanism has a number of drawbacks, which include added weight, introduction of extra assembly steps to weld the base plate to the support shaft, and creation of the opportunity for moisture trapped between the revolving plate and the base plate to rust the assembly. Further, as the thickness of the base plate increases, a moment arm is created between the revolving plate and the shaft.
Despite earlier efforts, there remains a need for an improved trailer hitch, having multiple hitch balls, which meets one or more of the following objectives. The trailer hitch should have a minimum of parts and be relatively easy to assemble. It should be relatively inexpensive to manufacture. The trailer hitch should be designed to maximize the mechanical advantage of the load bearing components, thereby maximizing its weight handling (towing) capabilities. It should be easy to service and maintain. The trailer hitch should be easy to operate, that is, easy to change from one hitch ball to another and easy to connect to a trailer. Further, the ball mount component of the trailer hitch should be interchangeable with and/or compatible with the receiver hitch component of standard trailer hitches.